For many areas of technology, thin is in, including laptops, phones, tablets, and solar panels. Shrinking a dimension can have a powerful impact on a device's properties, including drastically reducing cost, which is important if you want the technology to be widely adopted. Researchers at Stanford University have recently built the thinnest light-absorbing material in the world, which also has record-breaking efficiency.
Building something just nanometers in size can be very challenging, but it also enables one to precisely control a material's properties. In this case the material was comprised of trillions of gold nanodots, just 14 nm tall and 17 nm wide, atop a thin wafer with a thin-film coating covering it all. The thin film was applied using atomic layer deposition, which allowed the researchers to tune the system by manipulating the thickness of the coating around the dots. This tuning resulted in the light-absorber being able to absorb 99% of 600 nm light, which is reddish-orange in color. Such efficiency is not possible with larger materials in part because of how far the energized electrons have to travel to an electrode, but within this material it is a short trip.
The researchers are now looking into using materials other than gold, which was selected for its chemically stability, as other materials could be cheaper and be better suited for solar energy conversion. Ideally a solar cell can harvest energy from the entire visible spectrum, and not from a single frequency.
Source: Stanford University